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Why do humans still have body hair?
Hairs serve as motion detectors for alerting us to insects, like bedbugs, before they can bite us.
Wed, Dec 14 2011 at 8:20 AM
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Photo: Lee J Haywood/Flickr
Human body hair might seem to be useless on today's modern man, but it could help us detect parasites, researchers suggest, adding there's a chance our female ancestors preferred a bug-free mate, and so opted for hairier guys.
Humans appear relatively hairless compared with our ape relatives, but the density of hair follicles on our skin is actually the same as would be expected of an ape our size. The fine hairs that cover our bodies, which have replaced the thicker ones seen on our close relatives, are thought to be an evolutionary leftover from our hairy ancestors.
Now scientists find these fine hairs are useful after all — people with more of them are better at detecting bedbugs.
"I run a research group that seeks to understand the biology of bloodsucking insects," said researcher Michael Siva-Jothy, an evolutionary ecologist at the University of Sheffield in England. "Our aim is to find ways of controlling these insects effectively and thereby preventing the transmission of insect-vectored disease."
Investigators recruited 29 university student volunteers through Facebook and shaved a patch of hair from one of their arms. The scientists then tested how long it took the volunteers to detect bedbugs placed on each arm and how long it took the parasites to find a good place to feed on. (The bugs were removed before they started feeding.)
The researchers found that body hair significantly enhanced how well people detected the bedbugs, with participants noticing the bugs on the hairy arm quicker than they did when tested on the "hairless" arm, with the hairs serving as motion detectors. The hair also prolonged how long it took the parasites to find places to feed, presumably because they hindered movement, Siva-Jothy told LiveScience.
Men seemed better at detecting parasites — they are generally hairier than women because of higher testosterone levels. This does not necessarily mean that women are more likely to be bitten — blood-sucking insects likely prefer to bite hosts in relatively hairless areas such as ankles.
Although the researchers stress they are not saying that the differences in male and female body hair are due to parasites, they do speculate that in our evolutionary past women might have preferred men with fewer parasites on them — hairier men.
The scientists detailed their findings online Dec. 13 in the journal Biology Letters.
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We have indeed created man in the best of moulds, (4)At-Tin (QURAN)
This evolution joke has never ceased to amuse me. It has been proven that humans were humans millions of years ago and apes were apes. they appeared suddenly. there has been no evolution. Stop this propaganda already
you clearly have no idea what you are talking about.
I thought the world was only a few thousand years old according to the bible?
Can you please provide the links to this "proof" as i would be interested in reading it.
I do not think that 'proven' means what you think it does. Even ignoring the lie about 'no evolution', homo sapiens sapiens appeared on the landscape about 200,000 years ago. There are certainly no fossils of humans from 'millions of years ago'.
If there can be fossils of little fish there can be of humans to.
Care to provide this proof? Or at least tell us where to find it? Should make for fascinating reading.
Maybe we have hair because we are mammals? Just sayin'....
obviously, human beings still have body hair because God has not willed it off of us yet. He's busy not doing other things you'd expect from a benevolent loving creator being.
@ambassador I don´t think "theory" means what you think it means, because gravity is also a "theory" but things keep falling. Perhaps you should clarify your doubts by doing a bit of research.
Gravity is a law, homeboy, but I agree with the spirit of your post.
True and true, but particle theory seems to be standing up quite well. They just found another one, btw...
Oh, and germ theory - I'm still gonna take my pills!
So, the theory of evolution? Good enough for me :-)
It's amazing that this evolution theory explains everything from body hair to the colour of our eyes.
It's still a theory people, and you can't just use simplistic inference to explain things far more complex and intricate than we can even wrap our minds around. The probability of that our planet and indeed us as humans evolved from inanimate matter is nothing short of a mathematical impossibility.
what hair... I had all mine lasered
DOES NOT MAKE SENSE...
what about intraspecies diversity? do people in africa have more hair? some world areas have more bugs that's for sure. I can't find any relation!
What is more interesting is why our hair never stops growing? When was the last time you saw a chimp with pigtails? Yet as I look out the window I see several people with long hair! Yet our anthropologists would have us believe chimps are over 98% the same as us. Oh and by the way have you ever seen a chimp clipping its nails-no you won't!
CAn You even imagine how many Slight changes in a human body, all adding up with one another, That TWO percent ( 2% ) of difference in a Genetic Code would make? Exactly the amount of diference between any person you see at a zoo and any Ape youd see at the same one..
Yup.
Well I'd say that hair and toenails are about 2%. What else you got to base your argument on besides hair and toenails.
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